CODEWITHSUNDEEP
matlabfunctionmatrix
Macaronnos
Macaronnos

Reputation: 647

The fastest way to apply function to matrix in Matlab

I have Nx2 matrix A and a function f of 2 variables.

A = [1,2;3,4;5,6;7,8;9,0];
func = '@(x1, x2) sin(x1+x2)*cos(x1*x2)/(x1-x2)';
func = str2func(func);

I can apply function to matrix in a way like this:

values = arrayfun(@(x1,x2) func(x1, x2), A(:,1), A(:,2));

It seems to be faster than by for-loop, but still to slow for my program. I wonder if there is any other way to do it faster?

Edit. Functions are generated by the program. They are made by some simple functions like plus, minus, times, expl, ln. I don't know how to vectorize them.

Upvotes: 0

Views: 137

Answers (1)

Luis Mendo
Luis Mendo

Reputation: 112659

The fastest approach is to vectorize your function, if that's possible. Vectorizing can sometimes be done by just changing *, /, ^ into their element-wise versions .*, ./, .^. In other cases it may require use of bsxfun.

For your example function, vectorization is straightforward:

A = [1,2;3,4;5,6;7,8;9,0];
x1 = A(:,1);
x2 = A(:,2);
values = sin(x1+x2).*cos(x1.*x2)./(x1-x2);

Upvotes: 1

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